Driving sprocket-wheel.



UNITED (STATES rm 3. HOLT, 01f STOCKTON, CALII'OW.

PATENT OFFICE.

nnrvnm. sraoon'r-wmmn.

-To all whomz'tma concern:

Be it known t at I, PLINY E. Hour, a citizen of the United States, residing at .Stockton, in the county of San Joaquin and State of California, have invented new and useful Im rovements in Driving Sprocket- Wheels, 0 which'the following is a specification.

Thisinvention relates to sprocket driving wheels for use particularly in connection with endless flexible track such as employed in self-la ing track vehicles.

v The ob ect of this invention is to provide a novel and improved means in taking up the slack in a track, due to elongation or wear. v

In vehicles of this type the endless tracks are made up of a series of articulated link sections, the pin teeth of which engage alternate teeth on the sprocket driving wheel, the length of each link correspondin usually to the peripheral length of two teet By making alternate depressions between the teeth of the s rocket wheel of one depth and the intermediate depressions of a diflerentdepth and ad'usting t e chain so that its pin teeth enter t e deeper depressions at the outset, provision is made whereby slack can be taken up in the chain as the latter wears and be comes stretched, s'impl by shifting the chain on the rocket w eel so that the pin teeth of the enter the shallower depressions.

One form which my invention may assume is exemplified in the following descri tion and illustrated in the accompanying rawing, in which:

igure 1 shows a side elevation on a tractor truck mechanism of the self-laying track type, embodying my invention.

i 2 shows a detailed view of the driving sproc et wheel with a link in place thereon, as employed in my invention.

Fig. 3 shows a sectional view taken on a line of H of Fig. 2.

In the drawing I show a roller truck mechanism within a self-laying track (11), the latter running over a front blank idler wheel (12) and a rear driving sprocket wheel 13).- The track is made up of a series 0 articulated link sections, each comnsmg' side bars 14)" connected to ther' 2t one end by gu ii blocks, or' eeves, (15), and ('16) for g I receiving journal pins w:beneath-ale !v lpeelflcation of letters Iatent. Application filed December 7, i910. Serial no. 135,045.

Patented Mar. 5, 1918.

Teeth (17) are rovided for the driving sprocket wheel, eacli having a low base 18) at one side, and pitch diameter of whic is represented by the dotted lines (19), and a high base (20) at the other side, the pitch diameter of which is represented by dotted lines (21). Thus a sprocket wheel with various diameters is provided.

The links of the track chain are so proportioned relatively to the teeth of the sprocket wheel that each link receives two teeth, and as assembled and operated the gudgeon blocks (15) (which constitute the pin teeth of the chain) are arranged to enage the teeth of the sprocket wheel at the 0Wer base (18), as shown in Fig. 2. This is when the chain is new and unstretched; thereafter, as the teeth of the sprocket wheel wear and the chain becomes stretched, resulting in a great deal of slack in the chain, the latter is shifted relatively to the sprocket wheel so that the gudgeon blocks (15) en'- gage in higher bases (20). of the teeth. This will cause a ti hteningof the chain to the extent of the pitch lines (19) and (21), and also provides a new wearing surface for the gudgeon blocks (15) to work against.

ifi'erence in diameter of the Various changes in construction and arrangement of the several parts herein shown and described may be made without departing from the spirit of my invention, as disclosed in the appended claims.

What I claim, and desire to secure by Letters Patent is: V

1. In combination, a sprocket wheel, portions of which are of different pitch diameters and a chain running over said sprocket wheel and capable of being selectively operated in connection with said portions of different pitch diameters for the urpose stated. 2. In self-laying track vehicles, a toothed sprocket wheel, an endless flexible chain- ,track running over said sprocket wheel and comprising a series of link sections, said sprocket wheel having a lurali of teeth for each link section, the ases o the teeth engaged by the links being a difierentdistance from the center than those not engaged, for the purpose stated.

In a self-laying track vehicle, a toothed sprocket wheel having alternate depressions of one depth and intermediate depressions of a difl'erent depth, and an endless flexible chainmckrunmngovereaidwheeland comprising a series ofarticulated link secand at another time in the shallow deprestions, each link receiving two teeth, for the sions.

purpose stated. 5. The combination with achain track trac- 4. In a self-1a in track vehicle a toothed tor of means to take up wear in said track,

6 sprocket wheel avmg alternate depressions said means comprising a toothed sprocket 2c of one depth and intermediate depressions wheel having alternate depressions of oneof a different depth, and an endless flexible depth and intermediate depressions of a difchain track running over said wheel and ferent depth, for the purpose stated. comprising a series of articulated link sec- In testlmony whereof I have hereunto set 10 tions, each having a pin tooth to enter a demy hand in the presence of two subscribing 25 ression in the sprocket wheel, said pin teeth witnesses.

ing spaced a distance corresponding to th PLINY E. HOLT. peripheral length of two teeth, whereby the Witnesses: chain may be arranged to have its pin teeth R. E. MANN,

15 workat one in the de ep depressions FRANK H. Omsnom. 

